Spoilees
She can see the date people die. Thee date people die is not fixed, it can change. However red coloured dates indicate it is near impossible to change.
The third prince is evil we assume, and knows something about why she can do this ability. Apparently related to god and why the imperial family rules above religion.
Main female character is following the first price so that she can make her way to the capital (where the third prince told her to go if she wants answers). Along the way she is helping him with his crew and avoiding deaths as much as possible. She is also trying to figure out why she is related to his death, and why her death is in the past.
I need spoilers bc I'm actually so confused